Downhole jet unit for testing and completing wells

ABSTRACT

The invention relates to pumping engineering, mainly to downhole jet production units. The inventive downhole jet unit comprises a packer, a pipe column and a jet pump. An active nozzle and a mixing chamber are axially arranged in the body of the jet pump, and a pass channel provided with a mounting face for a sealing assembly with an axial channel is embodied therein. Said unit is also provided with an irradiator and a receiver transformer of physical fields. Said receiver transformer is arranged on the side of entry of a liquid pumped from the well into the jet pump and mounted on a cable passing through the axial channel of the sealing assembly. The output of the jet pump is connected to the pipe column above the sealing assembly. The input of a channel for feeding the pumped out medium of the jet pump is connected to a space around the pipe column below the sealing assembly. The input of a channel supplying a working medium to the active nozzle is connected to a space around the pipe column. A number of channels for feeding the pumped out medium are embodied in the body of the jet pump. The invention makes it possible to optimise dimensions of various elements of the unit, thereby increasing the operating reliability of the downhole jet unit.

FIELD OF INVENTION

[0001] This invention relates to the field of pumping engineering,mainly to downhole jet units for oil production.

PRIOR ART

[0002] Known in the art is a downhole jet unit comprising a jet pumpinstalled on the production string in the well and a geophysicalinstrument placed in the production string below the said jet pump (RU2059891 C1).

[0003] The said jet pumping unit enables to pump different extractedmedia, e.g., oil, out of the well with the simultaneous treatment of theextracted medium and the well formation zone, but the said unit providesfor supply of a working medium to the nozzle of the jet unit over thestring, which in some cases narrows the field of application of the saidunit.

[0004] The closest, as to its technical essence and the achievableresult, to this invention is a down-hole jet unit comprising a packer, apiping string and a jet pump, the body of the said pump comprising anactive nozzle and a mixing chamber axially arranged therein, and a passchannel being made with a mounting face for installing a sealingassembly with an axial channel, the said downhole jet unit is providedwith an irradiator and receiver-transformer of physical fields, which isarranged on the jet pump side for entry of the medium pumped out of thewell and is installed on the cable put through the axial channel of thesealing assembly, the output side of the jet pump is connected to thepiping string above the sealing assembly, the jet pump side for entry ofthe pumped out medium is connected to the piping string below thesealing assembly, and the input side of the channel for supplying theworking medium to the active nozzle is connected to the spacesurrounding the lifting pipe string, and several channels for supplyingthe pumped out medium are made in the body of the jet pump (RU 2106540C1).

[0005] The said downhole jet unit enables to perform various productionoperations in the well below the jet pump installation level by, interalia, reducing a pressure difference both above and below the sealingassembly. However, the said downhole jet unit does not enable to utilizeits possibilities in full due to non-optimal relationships betweendimensions of various components of the construction of the downhole jetunit.

DISCLOSURE OF INVENTION

[0006] The objective of this invention is to optimize the dimensions ofvarious components of the construction of the downhole jet unit and,owing to it, to raise the reliability of its operation.

[0007] The stated objective is achieved owing to the fact that thedownhole jet unit comprises a packer, a piping string and a jet pump, inthe body of which an active nozzle and a mixing chamber are axiallyarranged, and a pass channel is made with a mounting face for installinga sealing assembly having an axial channel, the said unit is providedwith an irradiator and receiver-transformer of physical fields, which isarranged at the jet pump side for entry of the medium pumped out of thewell and is mounted on the cable put through the axial channel of thesealing assembly, the jet pump output side is connected to the pipingstring above the sealing assembly, the input side of the channel forsupplying the pumped out medium of the jet pump is connected to thepiping string below the sealing assembly, and the input side of thechannel for supplying the working medium to the active nozzle isconnected to the space surrounding the lifting pipe string, and severalchannels for supplying the pumped out medium are made in the body of thejet pump, wherein, according to this invention, the diameter of eachchannel for supplying the pumped out medium is not less than the innerdiameter of the nozzle output cross-section, the diameter of the passchannel in the area of the mounting face is, at least, 1 mm less thanits diameter above the mounting face, the diameter of the axial channelin the sealing assembly is, at least, 0.01 mm larger than the diameterof the cable, the diameter of the sealing assembly is, at least, 2 mmless that the diameter of the inner hole of the tubes, the diameter ofthe irradiator and receiver-transformer of physical fields is, at least,2 mm less that the diameter of the pass channel in the area of themounting face, the diameter of the pass channel in the packer is, atleast, 2 mm larger than the diameter of the irradiator andreceiver-transformer of physical fields, and in the lower portions ofthe channels for supplying the pumped out medium positions are made forinstalling check valves or other devices.

[0008] The analysis of the operation of the downhole jet unit has shownthat the its reliability may be increased by making various componentsof the construction of the unit according to strictly defineddimensions. It has been found out, in particular, that in a case whereseveral channels for supplying the pumped out medium are made, thediameter of those channels may not be taken arbitrarily. It is due tothe fact that a too large diameter of the channels results in areduction in the strength of the unit, but a too small diameter of thosechannels results in lowering the capacity of the jet pump. Taking intoaccount that the jet pump capacity mainly depends on the flow rate ofthe working medium passing through the active nozzle, the diameter ofthe output cross section of the nozzle has been selected as the typicaldimension. It has been found out in this connection that it is notadvisable to make the diameter of the channels for supplying the pumpedout medium less that the inner diameter of the output cross section ofthe active nozzle. As to the upper limit, it should be defined by thestrength characteristics of the jet pump construction, and, first ofall, by those of the jet pump body. In each particular case this valueis to be determined individually. In the course of the unit operationstudies of different well modes are conducted. One has to install andremove the sealing assembly, and move, in the process of operation, theirradiator and receiver-transformer of physical fields along the well.It has been determined that it is not advisable to make the diameter ofthe pass channel in the area of the mounting face of the sealingassembly that it would be less than 1 mm less than the diameter of thepass channel above the mounting face, and the diameter of the sealingassembly itself should be made at least 2 mm less than the innerdiameter of the piping string. In the result, possible sticking of thesealing assembly in the piping string during installation or removal ofthe sealing assembly is precluded, and the reliable installation of thesealing assembly onto the mounting face is ensured. It has already beensaid that in the process of the unit operation it is necessary to movethe irradiator and receiver-transformer of physical fields along thewell and, at the same time, minimize the medium flow through the axialchannel of the sealing assembly. It has been achieved by making theirradiator and receiver-transformer of physical fields at least 2 mmless than the diameter of the packer pass channel and the diameter ofthe pass channel in the area of the sealing assembly mounting face, andthe diameter of the axial channel in the sealing assembly should be madethat it would be at least 0.01 mm larger than the diameter of the cable,on which the irradiator and receiver-transformer of physical fields isinstalled. In some cases, e.g., when carrying out repair and restorationworks at the well, a need arises to isolate the well after stopping thejet pump. In such a case the most convenient place for installing checkvalves is the lower portion of the channels for supplying the pumped outmedium. For this purpose the lower portions of the said channels areprovided with positions for installing check valves or other devicesnecessary for ensuring the operation of the unit.

[0009] Thus, the objective of the invention—to optimize the dimensionsof various components of the construction of the unit and, owing to it,raise the reliability of operation of the downhole jet unit—has beenachieved.

BRIEF DESCRIPTION OF DRAWINGS

[0010]FIG. 1 represents a longitudinal section of the disclosed downholejet unit.

[0011]FIG. 2 represents a longitudinal section of the unit without thesealing assembly and the irradiator and receiver-transformer of physicalfields.

[0012]FIG. 3 represents a longitudinal section of the sealing assembly.

BEST EMBODIMENT OF THE INVENTION

[0013] The downhole jet unit comprises a packer 1, a piping string 2,and a jet pump 3, in the body 4 of which an active nozzle 5 and a mixingchamber 6 are axially arranged, and a pass channel 7 is made with amounting face 8 for installing a sealing assembly 9 having an axialchannel 10. The unit is also provided with an irradiator andreceiver-transformer 11 of physical fields, which is arranged at theside of the jet pump 3 for entry of the medium pumped out of the welland is mounted on the cable 12 put through the axial channel 10 of thesealing assembly 9. The output side of the jet pump 3 is connected tothe piping string 2 above the sealing assembly 9. The input side of thechannel 13 for supplying the pumped out medium of the jet pump 3 isconnected to the piping string 2 below the sealing assembly 9, and theinput side of the channel 14 for supplying the working medium to theactive nozzle 5 is connected to the space surrounding the lifting pipestring 2, and several channels 13 for supplying the pumped out mediumare made in the body 4 of the jet pump 3. The diameter D₁ of eachchannel 13 for supplying the pumped out medium is not less that theinner diameter D₂ of the output cross-section of the nozzle 5. Thediameter D₃ of the pass channel 7 in the area of the mounting face 8 is,at least, 1 mm less than its diameter D₄ above the mounting face 8. Thediameter D₅ of the axial channel 10 in the sealing assembly 9 is, atleast, 0.01 mm larger than the diameter D₆ of the cable 12. The diameterD₇ of the sealing assembly 9 is, at least, 2 mm less that the diameterD₈ of the inner hole of the tubes 2. The diameter D₉ of the irradiatorand receiver-transformer 11 of physical fields is, at least, 2 mm lessthat the diameter D₃ of the pass channel 7 in the area of the mountingface 8. The diameter D₁₀ of the pass channel 16 in the packer 1 is, atleast, 2 mm larger than the diameter D₉ of the irradiator andreceiver-transformer of physical fields, and in the lower portions ofthe channels 13 for supplying the pumped out medium positions 15 (e.g.,threaded sections) are made for installing check valves (not shown) orother devices.

[0014] The jet pump 3 and the packer 1 on the piping string 2 arelowered into the well and are placed above the producing formation. Thepacker 1 is brought into the operating position, thus isolating theborehole clearance. The sealing assembly 9 and the irradiator andreceiver-transformer 11 of physical fields are lowered on the cable 12.Into the borehole clearance around the piping string 2 a working medium,e.g., water, salt solution, oil, etc., is pumped. The working mediumcomes from the borehole clearance through the channel 14 into the activenozzle 5 of the jet pump 3. Within a few seconds after the pumping ofthe working medium through the active nozzle 5 a stable jet is formed atthe nozzle output, which, going out of the nozzle 5, entrains thesurrounding medium into the jet pump, which results in a pressurereduction first in the channels 13 for supplying the pumped out mediumand then in the under-packer space of the well, thus creating pressuredrawdown onto the producing formation. The amount, for which thepressure is lowered, depends on the rate, at which the working mediumgoes through the active nozzle 5, which rate, in its turn, depends onthe pressure value of the working medium discharged into the boreholeclearance above the packer 1. In the result, the formation medium comesover the piping string 2 and through the channels 13 into the jet pump3, where it is mixed with the working medium, and the mixture of themedia, owing to the energy of the working medium comes over the pipingstring 2 out of the well and on the surface. During the pumping out ofthe formation medium the parameters of the pumped out formation mediumare monitored, and it is influenced with the irradiator andreceiver-transformer 11 of physical fields. Depending on a particulartask it is possible to move the irradiator and receiver-transformer 11of physical fields along the well.

INDUSTRIAL APPLICABILITY

[0015] This invention may be applied when testing, completing andoperating oil or gas condensate wells as well as when conductingworkover jobs thereon.

What is claimed, is:
 1. The downhole jet unit comprising a packer, a piping string and a jet pump, in the body of which an active nozzle and a mixing chamber are axially arranged, and a pass channel is made with a mounting face for installing a sealing assembly having an axial channel, said unit being provided with an irradiator and receiver-transformer of physical fields, which is arranged at the jet pump side for entry of the medium pumped out of the well and is mounted on the cable put through the axial channel of the sealing assembly, the jet pump output side is connected to the piping string above the sealing assembly, the input side of the channel for supplying the pumped out medium of the jet pump is connected to the piping string below the sealing assembly, and the input side of the channel for supplying the working medium to the active nozzle is connected to the space surrounding the lifting pipe string, and several channels for supplying the pumped out medium are made in the body of the jet pump, wherein the diameter of each channel for supplying the pumped out medium is not less than the inner diameter of the nozzle output cross-section, the diameter of the pass channel in the area of the mounting face is, at least, 1 mm less than its diameter above the mounting face, the diameter of the axial channel in the sealing assembly is, at least, 0.01 mm larger than the diameter of the cable, the diameter of the sealing assembly is, at least, 2 mm less that the diameter of the inner hole of the tubes, the diameter of the irradiator and receiver-transformer of physical fields is, at least, 2 mm less that the diameter of the pass channel in the area of the mounting face, the diameter of the pass channel in the packer is, at least, 2 mm larger than the diameter of the irradiator and receiver-transformer of physical fields, and in the lower portions of the channels for supplying the pumped out medium positions are made for installing check valves or other devices. 